Glossary
Interference fit
Presssitz
An interference fit means the bearing ring seat has dimensional interference with its counterpart, creating surface pressure after mounting that fixes the ring by friction and prevents creep under load. It is generally required for the ring carrying circumferential load – typically the inner ring with a rotating shaft and stationary load direction.
Pressing on expands the inner ring or contracts the outer ring, reducing radial internal clearance, which must be considered when selecting the clearance class. Mounting is done mechanically with fitting tools, thermally by heating the inner ring, or hydraulically. Mounting forces must never be transmitted through the rolling elements.